PV-thermal solar power assembly

ABSTRACT

A flexible solar power assembly includes a flexible photovoltaic device attached to a flexible thermal solar collector. The solar power assembly can be rolled up for transport and then unrolled for installation on a surface, such as the roof or side wall of a building or other structure, by use of adhesive and/or other types of fasteners.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Patent ApplicationNo. 60/141,467 filed Jun. 29, 1999.

BACKGROUND OF THE INVENTION

Solar thermal collectors have been made in the past in long extrudedstrips which are then installed by adhering to the surface of a buildingroof. Recent developments in the manufacturing of photovoltaic(PV) powercells using thin-film photovoltaic material deposited onto a thin sheetof metal or polymer has resulted in the ability to produce a flexiblesolar-electric power cell. This technique also allows the manufacturingof these power cells in continuous sheets.

SUMMARY OF THE INVENTION

The present invention is directed to the combination of a solar thermalcollector and a photovoltaic device, each designed to capture energy ina different way, and to provide an assembly with better performance andeconomics than may result from the application of the two productsseparately.

The first aspect of the invention is directed to a solar power assemblycomprising a flexible thermal solar collector and a PV device mounted tothe thermal collector to create a solar power assembly. The assembly mayhave sufficient flexibility so it may be transported in a roll to a usesite, unrolled and attached to a support at the use site. The thermalsolar collector typically includes a plurality of fluid passageways.

Another aspect of the invention is directed to a hybrid solar powersystem including a solar power assembly, comprising a flexible thermalsolar collector and PV device creating a flexible solar power assembly.An external heated fluid receiver, such as a heat exchanger, is fluidlycoupled to the thermal solar collector. An external device, such as aregulated power supply, is electrically coupled to the PV device.

A further aspect of the invention is directed to a method for making asolar power assembly. A flexible thermal solar collector and a PV deviceare joined to create a flexible solar power assembly. The assembly isrolled for transport to a use site.

A still further aspect of the invention is directed to a method forinstalling a solar power assembly on a support at a use site comprisingunrolling a solar power assembly from a roll, the solar power assemblycomprising a flexible thermal collector and a PV device mounted to oneanother. The solar power assembly is attached to the support with theflexible thermal collector located between the support and the flexiblePV device. The attaching step may be carried out using an adhesiveand/or clips.

An additional aspect of the invention is directed to a solar powerassembly comprising a polymer thermal solar collector and a PV devicemounted thereto. The polymer may be a flexible polymer, such as EPDM.

Another aspect of the invention is directed to a solar power unitcomprising a thermal solar collector and a PV device mounted thereto tocreate a solar power assembly. A collapsible glazing is mounted to thesolar power assembly to overlie the PV device for movement betweenupright, inflated and collapsed, deflated conditions.

These various aspects of the invention provide a number of advantages.The invention permits the solar power assembly to be simply and securelymounted to a roof or other support by, for example, attaching theassembly directly to a roof membrane with an adhesive; this reduces oreliminates the need for additional mounting structure and also mayeliminate the need for roof membrane-penetrating fasteners. Also, theassembly can take the place of the roof membrane by, for example,mounting strips of the solar power assembly adjacent to one another in ashingled fashion to form what is in essence a roof membrane. Themanufacture of a PV device and thermal solar collector as one assemblymay result in lower cost as well as simpler transportation andinstallation.

Other features and advantages of the invention will appear from thefollowing description which the preferred embodiments have been setforth in detail in conjunction with the accompany drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating joining of a length of aflexible thermal solar collector and a flexible PV device laminate tocreate a roll of a flexible solar power assembly;

FIG. 2 is an enlarged view of the roll of the solar power assembly ofFIG. 1 with a portion of the PV device laminate broken away to show thethermal solar collector;

FIG. 3 is an enlarged view of the outer end of the flexible solar powerassembly of FIG. 2 showing the series of fluid pathways formed in thethermal solar collector;

FIG. 4 illustrates a length of the solar power assembly of FIGS. 1-3mounted to a shingled roof membrane of a building;

FIG. 5 is a schematic representation illustrating the fluid andelectrical connections to the solar power assembly of FIG. 4;

FIG. 6 illustrates a roof membrane created by a shingled series ofadjacent lengths of the power assembly of FIGS. 1-5;

FIGS. 7A-7C illustrate an alternative embodiment of the invention inwhich adjacent thermal solar collectors can be joined using fluidcouplers between aligned fluid passageways and a clip to secure thejoint;

FIGS. 8A-8C illustrate enlarged cross-sectional views of threeembodiments of the PV device laminate of FIGS. 1-3;

FIGS. 9A-B illustrate an alternative embodiment of the invention inwhich an inflatable cover material is used above the photovoltaic devicelaminate; and

FIGS. 10A-B illustrate the use of clips for attaching a solar powerassembly to supporting shingles.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates in schematic form a roll 2 of a flexible thermalsolar collector 4 being joined to a roll 6 of a flexible photovoltaic(PV) device laminate 8, typically by the use of heat and/or adhesivesand/or pressure at position 10, to create an elongate solar powerassembly 12 which is wound into a roll 14.

FIG. 2 is an enlarged view of roll 14 and shows thermal solar collector4 and PV device laminate 8 which are joined to form solar power assembly12. Laminate 8 includes a series of PV devices 16 which areappropriately interconnected to obtain the desired electrical outputduring use.

FIG. 3 illustrates a series of fluid passageways 18 formed throughthermal solar collector 4. An appropriate fluid, such as water, ispassed through passageways 18 to collect heat from solar collector 4.Fluid may be caused to flow through passageways 18 by natural convectiveflow, by pumping or by a combination thereof.

In the preferred embodiment of FIGS. 1-3, PV device laminate 8 comprisesan amorphous silicon photovoltaic collector material deposited onto astainless steel substrate 19, or other PV material, such as copperindium diselinide on substrate of similarly flexible material. While itis preferred that PV devices 16 be flexible, PV devices may besubstantially rigid but shaped and sized so as not to impair the desiredflexibility of collector 4.

Thermal solar collector 4 is made of a polymer, preferably of a flexibleplastic or elastomer material such as polypropylene, PEX brandcross-linked polyethylene from Specialty Filaments, Inc. or EthylenePropylene Diene Monomer (EPDM). Thermal solar collector 4 may beextruded in long sections. Making thermal solar collector 5 of a polymerhas several advantages over conventional copper thermal solarcollectors: lower cost; there is a better area match between the PV andthermal loads due to the less efficient thermal collection efficiency ofpolymers; the maximum design stagnation temperature for polymer solarthermal collectors is lower than for conventional copper solar thermalcollectors so there is a better match with the maximum operatingtemperature of the PV device, typically about 80° C.; when the polymeris flexible, the solar power assembly may be flexible to permit theassembly to be stored and transported in rolls.

Solar power assembly 12 is preferably sufficiently flexible so that itmay be wound into a roll having a minimum diameter of about 60 cm (2foot), preferably about 30 cm (1 foot) and more preferably about 10 cm(4 inches). That is, power assembly 12 is flexible enough to permit itto be wound about a mandrel having a diameter of about 60 cm, preferablyabout 30 cm and more preferably about 10 cm.

Assembly 12 may conveniently be transported to a work site as a roll 14.Once at the work site an appropriate length of assembly 12 may beremoved from roll 14 and mounted to the support, such as roof membrane20 shown in FIG. 4. While various hold-down structures and fasteners maybe used to secure assembly 12 to roof membrane 20, solar power assembly12 may often be mounted to a roof or other support simply by using anadhesive without the need for specialized mounting structures. Also, thesolar power assembly may be formed into the desired lengths toappropriately fit a desired location. The invention facilitates not onlythe manufacturing of hybrid solar power assembly 12, it also facilitatestransport and installation of the solar power assembly. When adhesivesare used, the adhesives may supply all, or at least a majority of, thehold-down strength holding assembly 12 to the support. In an alternateembodiment, see FIGS. 10A and 10B, clips 23 may be used to secureassembly 12 to shingles 25 to supply all, substantially all, or at leasta majority of, the hold-down strength to the roof.

FIG. 5 illustrates schematically one way in which assembly 12 may beconnected for use. FIG. 5 illustrates a heat exchanger 21 connected toopposite ends 22, 24 of assembly 12 by a conduit 26. Ends 22, 24 aretypically in the form of manifolds to combine and distribute the fluidflow, typically a water-based liquid, from and to fluid passageways 18.The output from PV devices 16 is provided to a regulated power supply28, which typically may include appropriate control electronics, storagebatteries, an inverter, etc, by an electrical line 30. In lieu of heatexchanger 21, heated water, or other liquid, could be used directly; forexample, pre-heated water could be supplied from end 26 of assembly 12to a water heater with replacement water being directed to the end 24 ofassembly 12 from, for example, a municipal water supply, or water couldbe supplied from end 26 directly into a fluid reservoir, such as aswimming pool. Also, regulated power supply 28 could be replaced, forexample, by control electronics which would provide alternating currentto a user's dwelling and/or to a commercial electric power grid. Otheruses of heated fluid and electricity can also be made.

FIG. 6 illustrates a solar power assembly 12A in a form of numerousstrips of solar power assemblies 12 joined at their adjacent edges,typically in a shingled or other rain-shedding configuration.Alternatively, solar power assembly 12A could be manufactured as aunitary piece. Solar power assembly 12A itself could act as aroof-membrane itself. This can result in increasing the life of a roofmembrane or it may enable one to forego the use of a separate roofmembrane altogether. Solar power assemblies could also be made to act asside wall cladding for buildings. Roof membranes and side wall claddingare layers which protect the structures from the effects of theenvironment, primarily rain, and will be referred to generally asweather barriers.

FIG. 7A-7C illustrate an alternative embodiment of the thermal solarcollector 4 of FIGS. 1-3. Thermal solar collector 4A is shown to includefluid passageways 18A sized to accept fluid couplers 34. Adjacent endsof two thermal solar collectors 4A can be joined using fluid couplers34; the joint created can be secured through the use of a clip 36 asshown in FIGS. 7B and 7C. Such a joint may also be secured usingadditional fasteners and/or adhesives.

FIG. 8A is an enlarged cross-sectional view of one embodiment of a PVdevice laminate 8A made in accordance of the invention. Laminate 8Acomprises a top layer 40, typically of glass or a halogenatedhydrocarbon film such as Tefzel, from DuPont, or other suitablematerial. A typical thickness for top layer 40 is on the order of 50microns for material such as Tefzel while a typical thickness forencapsulant layer 42 is on the order of 0.76 mm (0.03 inch) for amaterial such as Ethyl Vinyl Acetate (EVA). Next comes an encapsulantlayer 42 typically made of EVA film. Third is the PV active layer 44.Below PV layer 44 is a PV substrate 46, typically made of stainlesssteel, aluminum, a polymer or some other suitable material. Next comes asecond encapsulant layer 48, which may or may not be made of the samematerial as encapsulant layer 42. Beneath encapsulant layer 48 is abackskin 50, made of a material such as Tedlar brand polyvinyl fluoridefilm from DuPont, Tefzel from DuPont, or aluminum foil. Beneath backskin50 is a third encapsulant layer 52. The bottom layer is a thermalcollector material layer 54. Encapsulant layers 42, 48 and 52 may alsobe characterized as adhesive layers. Adhesion between the various layersmay be accomplished using thermoplastic sheets, such as EVA,polyethylene or other suitable material. The bonding process willtypically use a lamination technique or direct adhesive application orboth. PV device laminate 8A illustrates a typical layering sequence. PVdevice laminate 8A may also be made by adding or subtracting variouslayers; for example, thermal collector material layer 54 may constitutethermal solar collector 4, thus eliminating the need for encapsulantlayer 52 and backskin 50.

FIG. 8B illustrates a PV device laminate 8B which is substantiallyidentical to laminate 8A with the exception of encapsulant layer 42B.The thickness of encapsulant layer 42B is increased to increase thethermal insulation above PV active layer 44. Doing so allows the solarpower assembly to operate at increased temperatures, thus increasing theheat flow to a fluid in the thermal solar collector. To increase thethermal insulation above PV active layer 44, the thickness ofencapsulant layer 42B may be increased from, for example, about 0.76 mmto as much as 6.4 mm (0.25 inch) causing encapsulant layer 42B to serveas both an encapsulant and a thermal barrier. The increased thermalinsulation may also be achieved by or aided by increasing the thicknessof top layer 40. Increasing the thickness of layer 42, when made of amaterial such as EVA, reduces thermal losses by an amount greater thanan equivalent thickness of air (see FIG. 8C) due to the lower thermalconductivity of EVA and the lack of convective currents in the EVA.Further, direct contact of encapsulant layer 42B with top layer 40 andPV active layer 44 reduces incident light losses compared with anequivalent air gap.

FIG. 8C illustrates an alternative embodiment of the PV device laminate8A of FIG. 8A. Laminate 8C is similar to laminate 8A but includes anoversheet 56 mounted to above top layer 40 by spacer 58 to create voidspaces 60 therebetween. Oversheet 60 may be of the same material as toplayer 40 or a different material suitable for placement above PV activelayer 44.

FIGS. 9A-B illustrate, in simplified schematic form, use of acollapsible glazing 62 above a PV device laminate 8D of assembly 12D.Collapsible glazing 62 is supported in its expanded, raised condition bythe dynamic pressure drop of a circulating operating fluid passingthrough thermal solar collector, the operating fluid being air, water,or some other fluid. Collapsible glazing 62 inflates during thermalcollection and falls slack or collapses during the generation ofelectricity only. Glazing 62 offers good thermal insulation duringthermal collection, and reduced stagnation temperatures during electriconly operation because the insulating layer between collapsible glazing62 and PV device laminate 8D is greatly reduced when the circulatingpump or fan is turned off.

Collapsible glazing 62 is preferably inflated by blowing air into theregion 64 between glazing 62 and assembly 12D. A fluid, such as air orwater, may be forced through passageways formed in assembly 12D (such aswith a fan, a pump or by convective forces); however, the passage of afluid through region 64 may be sufficiently efficient at removing heatso to eliminate the need for passage of a fluid through passageways inassembly 12D. Glazing 62 could, for example, incorporate hollow ribswhich could be filled with a fluid to cause the glazing to assume itsexpanded, raised condition shown in FIGS. 9A-B.

Modifications and variations can be made to the disclosed embodimentswithout departing from the subject of the invention as defined in thefollowing claims. For example, PV devices 16 could be mounted directlyto thermal solar collector 4.

Any and all patents, patent applications and printed publicationsreferred to above are incorporated by reference.

What is claimed is:
 1. A solar power assembly comprising: a flexiblethermal solar collector; a photovoltaic (PV) device mounted to thethermal solar collector to create a solar power assembly; and the solarpower assembly having sufficient flexibility to be transported in a rollto use site, unrolled and attached to a support at the use site.
 2. Theassembly according to claim 1 wherein the thermal solar collectorcomprises a plurality of fluid passageways.
 3. The assembly according toclaim 2 wherein the fluid passageways have open ends, and furthercomprising fluid couplers mountable to the open ends of the fluidpassageways so to permit said fluid passageways of plurality of saidthermal solar collectors to be fluidly connected to one another.
 4. Theassembly according to claim 1 further comprising: a unitary thermalsolar collector; and a plurality of said PV devices, said PV devicesbeing interconnected with one another and mounted to the unitary thermalsolar collector.
 5. The assembly according to claim 1 wherein the solarpower assembly is sufficiently flexible to be transported in a rollhaving a minimum diameter of about 60 cm or smaller.
 6. The assemblyaccording to claim 1 further comprising a flexible PV device laminate,joined to the flexible thermal solar collector, comprising a flexiblesubstrate carrying a plurality of said PV devices.
 7. The assemblyaccording to claim 1 where said PV device is flexible.
 8. The assemblyaccording to claim 1 further comprising a collapsible glazing mountedabove the PV device for movement between an upright, inflated conditionand a collapsed, deflated condition.
 9. A solar power assemblycomprising: a flexible thermal solar collector comprising a plurality offluid passageways; a flexible photovoltaic (PV) device laminate, mountedto the thermal solar collector to create a solar power assembly havingsufficient flexibility to be transported in a roll to a use site,unrolled and attached to a support at the use site; the flexible PVdevice laminate comprising a flexible substrate carrying a plurality ofinterconnected PV devices; the solar power assembly being sufficientlyflexible to be transported in a roll having a minimum diameter of about60 cm or smaller.
 10. The assembly according to claim 9 furthercomprising a collapsible glazing mounted above the PV device formovement between an upright, inflated condition and a collapsed,deflated condition, the collapsible glazing fluidly coupleable to asource of fluid to permit the collapsible to be selectively inflated ordeflated.
 11. A hybrid solar power system comprising: a solar powerassembly according to claim 9, an external heated fluid receiver fluidlycoupled to the thermal solar collector; and an external deviceelectrically coupled to the interconnected PV devices.
 12. A hybridsolar power system comprising: a solar power assembly comprising: aflexible thermal solar collector; and a photovoltaic (PV) device mountedto the thermal collector to create a solar power assembly havingsufficient flexibility to be transported in a roll to a use site,unrolled and attached to a support at the use site, an external heatedfluid receiver fluidly coupled to the thermal solar collector; and anexternal device electrically coupled to the interconnected PV devices.13. The system according to claim 12 further comprising a collapsibleglazing mounted above the PV device for movement between an upright,inflated condition and a collapsed, deflated condition, the collapsibleglazing fluidly coupleable to a source of fluid to permit thecollapsible glazing to be selectively inflated or deflated.
 14. Thesystem according to claim 12 wherein the external device comprises aregulated power supply.
 15. The system according to claim 12 wherein:the thermal solar collector comprises a plurality of fluid passageways;and the external heated fluid receiver comprises a heat exchangerfluidly coupled to the plurality of fluid passageways.
 16. The systemaccording to claim 15 further comprising a continuous loop fluid pathdefined in part by the plurality of fluid passageways and the heatexchanger.
 17. The system according to claim 12 wherein the externalheater receiver comprises a swimming pool.
 18. A method for making asolar power assembly comprising: joining a flexible thermal solarcollector to a photovoltaic (PV) device to create a flexible solar powerassembly; and rolling the flexible solar power assembly into a solarpower assembly roll for transport to a use site.
 19. The methodaccording to claim 18 wherein the joining step is carried out by joiningthe flexible thermal solar collector to a flexible PV device laminatecomprising a plurality of interconnected photovoltaic devices.
 20. Themethod according to claim 18 wherein the rolling step is carried outwith the roll having a minimum diameter of about 60 cm or smaller. 21.The method according to claim 18 further comprising joining aninflatable/deflatable, flexible glazing to the solar power assembly sothe flexible glazing overlies the PV device.
 22. A method for installinga solar power assembly on a support at a use site comprising: unrollinga solar power assembly from a solar power assembly roll, the solar powerassembly comprising a flexible thermal collector and a photovoltaic (PV)device mounted to one another; and attaching the solar power assembly toa support with the flexible thermal collector located between thesupport and the PV device.
 23. The method according to claim 22 whereinthe attaching step is carried out using an adhesive to provide at leasta majority of the hold-down strength holding the solar power assembly tothe support.
 24. The method according to claim 22 wherein the attachingstep is carried out using an adhesive to provide at least substantiallyall of the hold-down strength holding the solar power assembly to thesupport.
 25. The method according to claim 22 wherein the unrolling stepcomprises unrolling a plurality of said solar power assemblies.
 26. Themethod according to claim 25 wherein the attaching step is carried outso said solar power assemblies at least substantially cover the entiresupport.
 27. The method according to claim 26 wherein: the attachingstep is carried out with the support being a roof; and the plurality ofsolar power assemblies constitutes a weather barrier.
 28. The methodaccording to claim 25 further comprising interconnecting fluidpassageways of one thermal collector to fluid passageways of an adjacentthermal collector.
 29. The method according to claim 22 wherein theattaching step is carried out using clips to provide at leastsubstantially all of the hold-down strength holding the solar powerassembly to the support.
 30. The method according to claim 22 furthercomprising selectively fluidly coupling an inflatable/deflatable,flexible glazing, which overlies the PV device, to a source of fluid sosaid glazing assumes an upright, inflated condition spaced-apart fromthe PV device from a collapsed, deflated condition.
 31. A solar powerassembly comprising: a polymer thermal solar collector, the polymerthermal solar collector being made at least substantially of a flexiblepolymer; and a photovoltaic (PV) device mounted to the polymer thermalsolar collector to create a solar power assembly.
 32. A solar powerassembly 31 wherein the flexible polymer comprises EPDM.
 33. A solarpower unit comprising: a thermal solar collector; a photovoltaic (PV)device mounted to the thermal solar collector to create a solar powerassembly; and a collapsible glazing mounted to the solar power assemblyto overlie the PV device for movement between an upright, inflatedcondition and a collapsed, deflated condition.